1. Field of the Invention
The present invention relates generally to a mobile communication system, and in particular, to an apparatus and method for generating a Public Land Mobile Network (PLMN) list in a mobile communication system. In the apparatus and method, neighboring PLMNs are searched when a user chooses a PLMN manual selection mode using a mobile communication terminal having a Subscriber Identity Module (SIM) card supporting an Enhanced Operator Name String (EONS) associated with PLMN information. When no Local Area Code (LAC) is contained in the searched neighboring PLMNs, a PLMN list is generated using a Mobile Country Code (MCC) and a Mobile Network Code (MNC). Therefore, the PLMN list to be selected by the user is provided.
2. Description of the Related Art
A service area of a mobile communication system is determined by a Radio Access Network (RAN), including a Base Station (BS) and a Base Station Controller (BSC). In the service area, a region close to the RAN has a good signal sensitivity, but a region far from the RAN has a poor signal sensitivity. In addition, a lot of noise is mixed in a region outside the service area or a region where a lot of obstacles exist, resulting in the degradation of communication quality. In case a lot of service providers exist and a communication quality of a communication network currently connected is poor, a communication service can be received by accessing another neighboring communication network using a roaming service. To this end, the mobile communication terminal is designed to support a function of automatically or manually searching communication networks of other neighboring service providers and accessing the searched communication networks. The manual searching and accessing of the searched communication networks requires a procedure of searching networks and generating a network list and a procedure for accessing and registering a network selected from the network list by a user.
FIG. 1 is a schematic diagram of a conventional mobile communication system.
Referring to FIG. 1, a mobile communication terminal 100 accesses a first BS 110 via a wireless connection within a service area defined by the first BS 110 and registers in a first Mobile Switching Center (MSC) 120. In this way, the mobile communication terminal 100 receives a mobile communication service from the first MSC 120. Meanwhile, the communication service quality may be degraded when the mobile communication terminal 100 is located in a region outside the service area of the first BS 110.
When the region outside the service area of the first BS 110, where the mobile communication terminal 100 is located, belongs to a service area of an Nth BS 112 and the signal quality of the Nth BS 112 is poor, the mobile communication terminal 100 accesses the Nth BS 112 and registers in an Nth MSC 122. In this way, the mobile communication terminal 100 can continue to receive the mobile communication service using a roaming service.
In order to register in the Nth MSC 122 through the Nth BS 112 and receive the communication service of the Nth network, the mobile communication terminal 100 searches and selects the Nth network and requests a connection to the Nth network. Then, the mobile communication terminal 100 registers in the Nth MSC 122 in such a state that it is connected to the Nth network.
When a user of a mobile communication terminal having a Subscriber Identification Module (SIM) card supporting an Extended Operator Name String (EONS) chooses a PLMN manual selection mode, if MCC, MNC and LAC information is contained within information of PLMNs searched through a Radio Frequency (RF) channel, a PLMN list can be generated by loading PLMN Network Names (PNNs) matched with the corresponding information on the SIM card. However, if the LAC information is not contained in the information of the searched PLMNs, it is difficult to generate the PLMN list.
Therefore, there is a need for an apparatus and method that can generate the PLMN list even when the LAC information is not contained in the information of the searched PLMNs.